对不同碳化终温和经过H2、CO2预处理的Mo2C/Al2O3催化剂进行了POM催化活性评价与结构表征。结果表明，高碳化终温的Mo2C/Al2O3催化剂对于POM反应制合成气有高的甲烷转化率，CO和H2选择性，在580℃时H2预处理比CO2预处理的催化剂具有好的甲烷转化率和好的CO、H2选择性，但H2预处理时间过长会使CO和H2的选择性有所降低，CO2预处理会导致低的甲烷转化率和极低的CO和H2的选择性，XRD结果表明，在700～850℃之间碳化的样品均为β-Mo2C, BET比表面的测定结果表明随碳化终温的增加，Mo2C/Al2O3催化剂的比表面有所增加。

制备了一系列不同Mo2C担载量的Mo2C/Al2O3催化剂，利用微型固定床反应器对其POM反应进行了活性评价,并采用XRD、SEM和BET等方法进行了结构表征。实验结果表明，纯Mo2c催化剂在反应初期有较高的CH4转化率，但CO和H2的选择性很低，随着反应时间的增加，CH4转化率急剧下降，Mo2C担载量小于24.8%的摧化剂，随担载量增加，CH4转化率明显升高。同时，随着反应时间的增加，CH4转化率有所下降，CO和H2的选择性则明显升高。Mo2C担二项式国量在35.4～42.5%的摧剂，具有好的CH4转化率和CO、H2选择性，但担载量过高时，CH4转化率会随反应时间的增加而下降。结构表征表明，未担载的和担载的碳化物催化剂均为β-Mo2C，担载量小于10.6%，Mo2C高度分散于Al2O3表面，担载量较高时，Mo2c颗粒变大，比表面减少。

A series of Na-W-Mn/SiO2 catalysts with different sodium, tungsten, and manganese contents (wt.%) were prepared and their catalytic performance for the oxidative coupling of methane (OCM) was evaluated in a continuous micro-reactor. The structural properties of the catalysts have been characterised using XPS, laser Raman spectroscopy (LRS), and X-ray diffraction (XRD). The results show that the catalysts containing Na, W, and Mn between the range of 0.4-2.3, 2.2-8.9, and 0.5-3.0 wt.%, respectively, had high CH4 conversion and high selectivity to C2 hydrocarbons in the OCM reaction. The addition of sodium to the catalyst is believed to bring about the migration of manganese to the catalyst surface, as both elements are found in high concentrations in this area. CH4 conversion and the selectivity to C2H4 are closely related to the surface Mn concentration of the catalysts. Both Na-O-Mn and Na-O-W act as the active centres of the catalysts for the oxidative coupling of methane. The catalyst surface is mainly covered with Na and O, while the Mn and W are present in the sub-surface of the catalyst. There is a synergic effect of sodium, tungsten, and manganese components, and the Na2W2O7 crystalline phase is active for the oxidative coupling of methane.

A series of M-W-Mn/SiO2 catalysts (M=Li, Na, K, Ba, Ca, Fe, Co, Ni, and Al) have been prepared and their catalytic performance for the oxidative coupling of methane (OCM) was evaluated in a continuous-flow microreactor. The structural properties of the catalysts have been studied using X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). In the trimetallic catalysts studied, there was evidence for WO4 tetrahedron on the surface in the Li-, Na-, and K-W-Mn/SiO2 catalysts, which is mainly present in the subsurface of the Ba-W-Mn/SiO2 catalyst. It appears that the WO4 has a strong interaction with the α-cristobalite support and is stabilized in the Na-and K-W-Mn/SiO2 catalysts. However, the WO4 species appear to be less stable in Li-or Ba-W-Mn/SiO2 catalysts, in which the support turns into quartz SiO2 or amorphous SiO2. The WO4 tetrahedron on the catalyst surface appears to play an essential role in achieving high CH4 conversion and high C2 hydrocarbon selectivity in the OCM reaction. Calculations suggest that the WO4 tetrahedron interacts with the CH4, giving suitable geometry and energy matching with CH4, and this may account for the high OCM activities.

The adsorption of water on the surfaces of ultradispersed diamond UDD.powder obtained from explosive detonation and modified by treatment in different gases under high temperatures is investigated by FTIR method. It is found that UDD adsorbs atmospheric water quickly and in the IR region of OH stretching vibration of water, a broad asymmetric band envelope centered at 3412 cmy1 with shoulders at 3575 cmy1 and 3240 cmy1 appears soon after the sample pellets are exposed to air. The amounts and the initial rates of water of adsorption are different for UDD modified by different gases. Based on the experimental results three forms of adsorbed water are suggested. q1998 Elsevier Science B.V. All rights reserved.